splatDiagonal method
Set the diagonal of the matrix.
Implementation
void splatDiagonal(double arg) {
  _m3storage[0] = arg;
  _m3storage[4] = arg;
  _m3storage[8] = arg;
}
Set the diagonal of the matrix.
void splatDiagonal(double arg) {
  _m3storage[0] = arg;
  _m3storage[4] = arg;
  _m3storage[8] = arg;
}